Before you think that’s so far-fetched, let me remind you of Windows 7 being run on a Nook Touch — of course, this is via VNC remote control, but I think how the Nook handles the windows and other UI elements for Windows might apply to Macintosh too:

Original Macintosh: 68000 Motorola CPU at a blistering 8MHz(!), 128K(!) of RAM, and 512×342 screen